The main objective of this study is to develop an innovative polymeric primer (PP) containing different concentrations of the catalyzing agent titanium tetrafluoride (TiF4), which can be used in in-office dental bleaching, aiming to increase the aesthetic efficacy, prevent morphological alterations in the enamel treatment and reduce the cytotoxicity of the therapy. For this, enamel/dentin discs will be stained and then bleached for 45 minutes (1 session) with a bleaching gel containing 35% H2O2. The gel will be applied on enamel previously coated with PP containing different concentrations of TiF4 (2 mg/mL, 6 mg/mL or 10 mg/mL) associated or not with photoirradiation with the Violet LED (15 minutes). As a positive control, the same gel will be applied directly on the enamel, and in the negative control, no treatment will be performed. The best concentration of TiF4 present in the PP will be determined by screening the whitening efficacy, using a UV-reflection spectrophotometer (CIE L*a*b* System). Then, the same treatments will be performed to evaluate the microhardness. Then, the trans-enamel dentinal cytotoxicity of bleaching therapies will be evaluated, using the protocol where standardized enamel/dentin discs are adapted in artificial pulp chambers. After completing the therapies, the extracts (culture medium + components of the diffusion of bleaching gels) will be obtained and applied on odontoblast-like MDPC-23 cells, which will be evaluated for viability (MTT). The amount of H2O2 diffused by the discs will also be determined (Leuco-crystal violet/Peroxidase). The numerical data obtained will be submitted to specific statistical analysis.
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